Bag molding apparatus



` June 12, 1945- w. A. LlPPlNcoTT l A BAG MOLDING APPARATUS Filed 061:. 27, 1943 lllllllll NV'NTOL/ @fe/As' O4. PMAM,

Patented June 12, 1945 BAG MoLmNG APPARATUS Wells A. Lippincott, Evanston, Ill., assig'nor to Ideal Roller & Manufacturing Company, Chicago, Ill., a corporation of Illinois Application october 27, 1943, serial No. 507,808

2 Claims.

This invention relates to apparatus for molding open neck bags of rubber or like material. More particularly, the invention relates to molding apparatus in which the interior of the bag is dened by the external surface of a mandrel, and the external surface is formed by two separable parts collapsed around the mandrel. y

YThe primary object of the invention is to provide molding apparatus of the above character by which the intended shape of the bag may be achieved even through different parts of the bag are composed of materials having different ow characteristics in the plastic state.

The invention also resides in the novel structural character of. the means for carrying out the foregoing.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawing, in lwhich Figures 1 and 2 are fragmentary diametrical cross-sectional views of a mold set-up embodying the present invention, the mold being open and closed respectively.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawing and will herein describe in detail the preferred embodiment. It is to be understood, however, that I do not intend to limit the invention by such disclosure, but aim to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

In the drawing, the invention is embodied in an apparatus for molding a bag of the type Acornmonly used in hydraulic accumulators comprising two cups and 6 joined at their open ends and having an annular ange l formed around the neck 8 of the bag. The cups may be of different wall thickness, and, in this instance, the cup 5 is composed of rubber material which, in the plastic state and at the molding temperature, is less owable than the material of which the cup B is formed. y

The mold proper comprises two parts 9 and I0 having semi-spherical cavities II and I2 which, by virtue of interfitting projections I3 and I4, register accurately when the mold is closed as shown in Fig. 2. Herein, the part 9 is supported on the lower platen I5 of'a suitable press. The upper part III is connected as by screws I6 to a block I1 which is engaged by the upper platen I8. Heating of the mold parts may be by conduction from the press platens. The external shape of the bag neck and the adjacent end of the cup 5 is defined by a ring I9 disposed in a groove r2|) at the bottom of the cavity I2 and held remov` ably in place by a spring detent 2I.

The internal surface of the bag is contoured according to the exterior of a mandrel 22 which is removably mounted onthe mold part I0 and is slidable relative thereto axially of the cavity I2. In this instance, the mandrel is rigid with a stem 23 which fits into a sleeve 24 slidable in a bore 25 of the mold part I0 and the block I'I. A screw 26 threads into the end of the stem with its head seated in a socket 21 in the upper end of the sleeve. The sleeve and stem are thus connected rigidly, but, after withdrawal of the screw, the mandrel may be separated from the part- I0 to permit removal of the finished bag from the mandrel. In the loading position (Fig. 1) a flange 28 rigid with the sleeve 24 rests on a ledge 29 of the mold part I 0 thereby supporting the mandrel Within the separated mold cavities.

Finalpositioning of the mandrel in the two cavities I I and I2 as the mold is closed is effected by av stop formed in the present instance by an annular shoulder 3B on the part I!) immediately adjacent the sleeve 24. The stop surface is engaged by a raisedsurface 3| on the top of the mandrel. When the stop is thus engaged, the exterior of the mandrel will be spaced accurately from the wall of the cavity I2 thereby determining the wall thickness of the Cup 5 and the neck ilange 'I.

Separate bodies 32 and 33 of the rubber materials for forming the two bag parts are placed in the cavities II and I2 'as shown in Fig. 1. The body 33 is a ring encircling the lower end of the sleeve 24 adjacent the mandrel. With the mold thus loaded, the platens are moved together gradually to form the bag. In this operation, both compounds soften and now around the cavities lling the spaces between the exterior of the mandrel and the interior of the parts I0 and II, the excess iiowing into a flash cavity 34. f

When, as herein contemplated, the cup 5 is made of material which is less flowable than the material of the cup at the molding temperature, this material will offer greater resistance to the motion of the mandrel 22 relative to the mold part I0 than the body 32 offersto the advance of the mandrel with the result that too much of the more plastic compound is squeezed out between the upper and lower decks of the mold belfore the latter becomes fully closed. To avoid this condition, the invention contemplates the provision of power actuated means operable independently of the platen motions to overcome .lower cavity I I.

the greater resistance offered by the plastic body 33 and move the mandrel into the cavity l2 so as to bring it against the stop 30 and effect proper distribution of the two materials in the plastic state Herein, this means is actuated by uid pressure and comprises a piston 35 formed by the flange 28 on the sleeve 24 and slidable in a cylinder 3E whichhis formed by counter-boring the mold part '-l'l. L Pres'sue fluid "s'u'ch "as 'compressed air from va suitable source 31 may be admitted to the cylinder beneath the piston through a passage 38, suicient pressure being thus applied to offset the difference in the resistances-oered -by the bodies 32 and 33 to the mandrel motion. The flow of pressure iiuid may Be dnti'lledma a'll-"y by a hand valve 39 or automatically, if `lesirei,in response to the movement of the platen "1% in vthe closing of the mold. The otherend 'of thecylinder is Vented through a passage 40.

In the molding operation, the power 1actuator operates in the following manner.r After loading of the-mold as shown inUFig. 1, pressure fluid is admitted to the cylinder 36 to raise the mandrel, and the platen'l is lowered. Under this added upward force, the mandrel moves` into the cavity l2 and comes against the stop 30 before -its lower portion reaches its'nal position `(lig. 2) in the As a` result, accurate positioning of the mandrel within the mold is assured and the two rubber, materials are distributed properly in spite of their different -flow characteristics. l

The air pressure may be released as ysoon as the mold is closed. If desired, air may, after withdrawal of the screw 26, be admitted kabove the piston 35 through the passage 40 to facilitate lowering of the mandrel.

I claim as myinvention:

1. Apparatus rfor molding a bag or the like having an opening at the top and upper and lower portions made of materials having different Yflow characteristics during molding and comprising, in combination, upper and lower inold parts adapted respectively to 'shape the outer surfaces of said `upper and low'e'r bag ,portions of diffrent materials, means supporting said upper and flower mold parts for. relative mvme'nt in 'a of the mandrel toward the upper mold part to provide proper spacing between the mandrel and upper mold part, and power operated means on 'Said Yshaft for moving the mandrel relative to said upper mold part to a position against said stop and for holding such position prior to the closing of the upper and lower mold parts.

n 2. lApparatus for molding a bag or the like having an ropening at the top and comprising, in combination, Vupper and lower mold yparts adapted to shape the outer surfaces of the bag, means supporting said upper and lower -mold parts Yfor movement toward each other in a straight line and into engagement to form a cavity correspond'- ing in `shape to the external contour of the bag, a mandrel having external contours yadapted to form the internal surface of the bag and define the opening in the top of the bag, a shaft ex'- tending fro'm the mandrel at theopening forming :portion thereof an'd supported for endwise movement i'n said straight line vto carry the mandrel toward and vaway from said upper mold part, means on said upper 'mold part defining a fluid cylinder, a piston slidable in said cylinder and connected to said shaft for moving said shaft an'd mandrel under fluidpressure applied to said cylinder, Yand 'a stop for limiting movement of the mandrel toward the upper mold part and to provide proper spacing betwe'en the mandrel and up- 'per mold part, said upper and lower mold parts having faces adapted to seat together after the movement of the lmandrel into lproper position with respect to the upper mold part 'for closing 'and completing the mold.

WELLS A. LIPPINCO'I'I. 

